Avalanche and Heavy Snow in California, March 2 to 4, 2009

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE RENO NV
451 AM PST MON MAR 2 2009

CORRECTED

.SHORT TERM...
FRUSTRATING STORM SO FAR AND GFS HAS FAR OUTPERFORMED THE NAM THE
LAST 24 HRS. IT WAS BETTER ON THE WINDS AND PRECIP SO FAR WITH
MORE SPILLOVER THAN EXPECTED FOR AREAS SOUTH OF A SUSANVILLE TO
GERLACH LINE. WILL BE FOLLOWING THE GFS MORE CLOSELY...BUT AT
LEAST THE 06Z NAM LOOKS BETTER WITH REGARD TO WINDS AND SPILLOVER
THROUGH TONIGHT. BEYOND...NAM IS SHOWING ITS USUAL BIASES OF
DRY/NOT MUCH SPILLOVER WHEN CONDITIONS ARE FAVORABLE.
STILL...CONFIDENCE IN THE OVERALL FORECAST IS NOT ALL THAT HIGH
GIVEN RECENT MODEL PERFORMANCE. WHAT FOLLOWS BELOW IS MY BEST GUESS
AND REASONING FOR IT.

TODAY...WINDS STILL SLOW TO COME BACK UP...ALTHOUGH THEY ARE JUST
BELOW ADVISORY FOR SOME AREAS IN RENO-MONO. DO EXPECT THE WINDS TO
INCREASE AGAIN TODAY...BUT IT WILL BE MORE GRADIENT DRIVEN THAN
DOWNSLOPE. SFC LOW PROGGED BY MODELS TO DEEPEN OVER CNTRL NV WITH
H7 WINDS OF 55 KTS BY AFTERNOON. EXPECT ADVISORY LEVEL WINDS FROM
I-80 SOUTH IN RESPONSE TO THIS...AND IT WILL BE MORE WIDESPREAD
THAN MOST OF OUR WIND EVENTS AS IT IS GRADIENT AND NOT MTN WAVE
DRIVEN. WILL KILL WARNING FOR RENO...EVEN THOUGH WE NORMALLY DO
NOT DO THIS HERE...AS THE STATEMENT NEEDS TO BE EXTENDED FOR THE
SIERRA FRONT AND WINDS WONT MAKE IT TO WARNING...EXCEPT PERHAPS
GALENA. FOR TAHOE-LASSEN...WINDS WILL REMAIN BELOW ADVY THROUGH
THE MORNING AND THOUGH THEY WILL ALSO INCREASE THIS
AFTERNOON...PRECIP WILL INCREASE AS SNOW LEVELS FALL AND ANOTHER
STATEMENT OUT TO COVER THIS. CANCELLING THE ADVISORY FOR THOSE
ZONES. WILL LEAVE ZONES 1/4 AS IS...AND MONO STILL SNOWING ABOVE
7000 FEET...SO WILL LEAVE WINTER WEATHER ADVISORY OUT UNTIL
18Z...ALTHOUGH DAY SHIFT MAY NEED TO EXTEND OR REPLACE WITH
ANOTHER WIND ADVISORY.

AS FAR AS PRECIP...BAND HAS STALLED SOUTH OF HWY 50...ALTHOUGH IT
IS FINALLY BREAKING UP ATTM. STILL...VERY CONVECTIVE UPSTREAM WITH
SHOWERS DEVELOPING OVER CNTRL CA. EXPECT THIS TO CONTINUE AND
BECOME EVEN MORE WIDESPREAD THIS AFTERNOON. CHCS OF SPILLOVER
GOOD NORTH OF HWY 50 THIS AFTERNOON WITH AN UNSTABLE ENVIRONMENT
DEVELOPING AND JET SAGGING SWD TO NEAR HWY 50 BY 00Z TODAY.
STILL...SHOWERS WILL BE MOST NUMEROUS IN THE SIERRA TODAY.
EXCEPTION WILL BE AS COLD FRONT SAGS SWD THIS AFTERNOON AND
TONIGHT. ALONG THE FRONT...INSTABILITY...LEFT EXIT REGION OF THE
STRONG JET...STRONG 65 KT CROSS-BARRIER 700 MB FLOW...AND GOOD
FGEN ALONG THE COLD FNT VERY FAVORABLE FOR SPILLOVER. EVEN THE NAM
SEES THIS AND SHOWS 1/4 INCH OF RAIN IN RENO. WILL HAVE HIGHEST
POPS THIS EVENING TO ACCT FOR IT.

AS FAR AS SNOW LEVELS...THEY HAVE BEEN LOWER THAN INITIALLY
THOUGHT AND ARE CURRENTLY RUNNING ABOUT 6500 FEET NORTH TO 7000
FEET I-80 SWD. EXPECT THEM TO ONLY SLOWLY DROP BY 500 FEET THIS
AFTERNOON. WILL SEE THEM RAPIDLY DROP TO VALLEY FLOORS THIS
EVENING BEHIND THE FRONT. THERE IS A CHANCE AN ADVISORY FOR THE
SNOW IS NEEDED JUST BEHIND THE FRONT FOR THE SURPRISE VALLEY SWD
TO DOUGLAS CTY. HOWEVER...HOW QUICKLY THE SNOW LEVEL FALLS IS IN
QUESTION. RIGHT NOW GUT FEELING IS IT WILL BE MORE RAIN THAN SNOW
FOR THESE AREAS...ALTHOUGH DAY SHIFT WILL HAVE TO REVISIT THIS.

GIVEN THE FCST FOR TAHOE/LASSEN...WILL UPGRADE CURRENT ADVISORY TO
WARNING AND EXTEND THRU 12Z WED. STORM WILL BE MOST IMPRESSIVE TUE
INTO TUE NIGHT...BUT STILL SHOULD SEE ABOUT 1+ FEET THROUGH
MIDNIGHT TONIGHT ACROSS THE HIGHER PASSES WITH A FEW INCHES AT
LAKE LEVEL FOR TAHOE AND DOWN TO 5000 FEET IN LASSEN CTY.

FINALLY...NEED TO MENTION POTENTIAL THUNDERSTORMS TODAY AS MODELS
INDICATE -2 TO -4 LI FROM EAST SLOPES OF THE SIERRA INTO
PERSHING/CHURCHILL COUNTIES NORTH OF HWY 50. WILL ADD ISOLD
THUNDERSTORMS HERE. ONE INHIBITING FACTOR IS THE POTENTIAL STRONG
WIND SHEAR. IF ANY STORMS CAN REALLY GET GOING...DOUBTFUL...THEY
COULD PRODUCE SOME REALLY STRONG WIND GUSTS. BEST CHANCE OF THIS
HAPPENING IS NEAR THE COLD FRONT LATE THIS AFTERNOON AND EVENING.
POTENTIAL IS LOW...BUT IT IS THERE.

TUESDAY...ANOTHER WAVE DEVELOPS AHEAD OF THE MAIN LOW AND MOVES
IN. EXPECT SNOW TO CONTINUE FROM TAHOE-NWD WITH PERIODS OF
SPILLOVER INTO WRN NV WITH SNOW LEVELS NEAR THE VALLEY FLOORS.
FURTHER SOUTH ACROSS MONO-MINERAL COUNTIES...JET REMAINS NEAR HWY
50/I-80 SO DO NOT EXPECT MUCH SPILLOVER THERE. JUST SOME SNOW NEAR
THE SIERRA CREST RAPIDLY DROPPING OFF TO THE EAST. IN FACT...S END
OF LAKE TAHOE IS LIKELY TO BE QUITE A BIT DRIER THAN N END GIVEN
THE PROGGED JET STREAM LOCATION.

IMPORTANT NOTE...ALL OF WHAT I SAID ABOVE MAY BE MOOT. MANY
ADJUSTMENTS WILL LIKELY BE NEEDED WITH THIS CURRENT STORM AS IT HAS
PROVEN TO BE VERY FLUID. MODELS HAVE NOT HAD THE GREATEST TRACK
RECORD THIS WINTER...SEE DISCUSSION 24 HRS PRIOR FOR EVIDENCE. VERY
FRUSTRATING TO SAY THE LEAST.

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...
PRECIPITATION WILL BE CONTINUING ACROSS THE REGION TUESDAY NIGHT AS
THE UPPER LOW REMAINS QUASI-STATIONARY OFF THE NRN CALIFORNIA COAST.
THE MEDIUM RANGE MODELS ARE SHOWING A VORT MAX ROUNDING THE BASE OF
THE MAIN LOW TUESDAY NIGHT.  THE NAM...GFS...UKMET AND ECMWF ALL
SHOW THIS FEATURE IMPACTING THE NRN AND CNTRL SIERRA WITH ADDITIONAL
SNOWFALL.  SNOW LEVELS WILL RANGE FROM AROUND 3500 FEET IN THE NRN
SIERRA AND NWRN NEVADA TO AROUND 5500 FEET IN MONO COUNTY CA AND
MINERAL COUNTY NV.  THIS WILL ALLOW SNOWFALL TO CONTINUE TO REACH
THE VALLEY FLOORS ACROSS THE KREV CWFA.

ON WEDNESDAY THE GFS AND EURO SHOW A JET MAX TAKING THE VORT MAX
EAST INTO THE GREAT BASIN.  THIS WILL PUSH THE MAIN AREA OF PRECIP
TO THE SOUTH INTO MONO COUNTY.  PRECIPITATION SHOULD START TO TAPER
OFF IN THE NRN SIERRA AND NWRN NEVADA.  HOWEVER SNOWFALL SHOULD
CONTINUE AS THE UPPER COLD POOL MOVES OVER THE AREA AND CONTRIBUTES
TO LLVL INSTABILITY AND INCREASED SNOWFALL RATES.  BY WEDNESDAY
NIGHT BOTH MODELS SHOW THE COLD FRONT MOVING INTO CNTRL NEVADA WITH
A COLDER AIR MASS FILTERING INTO THE AREA.  AS A RESULT LOW
TEMPERATURES WEDNESDAY NIGHT WILL BE 3 TO 6 DEG F COLDER THAN THE
READINGS FOR TUESDAY NIGHT.  O'HARA

.LONG TERM...THURSDAY THROUGH SUNDAY...
CONTINUED UNCERTAINTY IN THE LONG TERM BEYOND THURSDAY WITH
SIGNIFICANT MODEL DIFFERENCES.  UPPER TROUGH ON THURSDAY HAS
CONTINUED TO TREND WESTWARD WITH BOTH THE ECMWF AND GFS NOW AS FAR
WEST AS 130W.  THIS WOULD BRING LESS OF A CHANCE FOR PRECIPITATION
DURING THE DAY ON THURSDAY.  KEPT GOING FORECAST PRETTY MUCH AS IS
ON THURSDAY...THE GFS WANTS TO BRING A FAST MOVING SHORTWAVE TROUGH
ACROSS THE AREA WHICH WOULD LEAD TO SNOW SHOWERS THROUGHOUT THE
DAY.  THE MAIN LOW WILL CONTINUE TO DROP SOUTH BY THURSDAY NIGHT
TAKING THE BEST ENERGY WITH IT AND BRINGING PRECIPITATION TO AN END
BY FRIDAY MORNING.

BIG DIFFERENCES START ON FRIDAY...THE ECMWF CUTS OFF THE LOW THAT
WILL IMPACT ON THURSDAY WELL OFF THE CA COAST AND DROPS A TROUGH
INTO THE NORTHERN ROCKIES.  THE GFS SWINGS THE LOW INTO SOUTHERN CA
AND DROPS A SECONDARY LOW DOWN THE PACIFIC NW COAST.  THE GFS HAS
REMAINED CONSISTENT WITH THIS SOLUTION FOR THE PAST SEVERAL
DAYS...HOWEVER THE TRACK IS ON THE FAR RIGHT OF ITS ENSEMBLE
MEMBERS.  A QUICK LOOK AT THE 06Z RUN CONTINUES TO REMAIN CONSISTENT
IN DROPPING THE LOW SOUTH ALONG THE WEST COAST TO OVER CENTRAL NV BY
SATURDAY AFTERNOON.  HAVE BEGUN TO PAY A BIT CLOSER ATTENTION TO THE
ECMWF SOLUTION WITH A FEW OF THE GFS ENSEMBLE MEMBERS AND A MAJORITY
OF THE CANADIAN ENSEMBLES TRENDING WITH THE CUT OFF LOW SOLUTION OF
THE ECMWF.

THE GFS SOLUTION WOULD CONTINUE TO BRING COLD WET CONDITIONS TO THE
AREA THROUGH SATURDAY WITH THE POTENTIAL FOR HEAVY SNOWFALL ALONG
THE SIERRA CREST AND LIGHTER ACCUMULATIONS INTO WESTERN NV BOTH
FRIDAY AND SATURDAY WITH THE LOW DROPPING OVERHEAD AND CLEARING THE
AREA ON SUNDAY.  THE ECWMF SOLUTION KEEPS THE AREA DRY FRIDAY AND
SATURDAY AS THE UPPER LOW REMAINS STATIONARY WELL OFF THE CA COAST
BEFORE BEING KICKED OUT ACROSS SOUTHERN NV ON SUNDAY.  THIS WOULD
BRINGING INCREASED PRECIPITATION..ESPECIALLY ACROSS OUT SOUTHERN
ZONES FOR SUNDAY.  FOR NOW LEFT THE GOING FORECAST WITH LOW POPS
THROUGH THE EXTENDED GIVEN THE UNCERTAINTY IN ANY SOLUTION AT THIS
POINT.  TRENDS WILL HAVE TO BE MONITORED OVER THE NEXT COUPLE OF
DAYS TO SEE IF WE CAN GAIN ANY INCREASED CONFIDENCE IN ANY OF THE
MODEL SOLUTIONS AND START TO PINPOINT WHAT AREAS MAY SEE
PRECIPITATION THROUGH SUNDAY.  MOZLEY

&&

.AVIATION...
MAIN CONCERN IS WIDESPREAD MVFR CIGS/VIS IN SIERRA THRU 02Z WITH
SHRA AND LCLLY IFR AT TIMES IN HEAVIER SHOWERS. EXPECT CD FNT TO
MOVE THRU FROM 02-04Z WITH RAIN CHANGING TO SNOW FOR KTVL/KTRK AND
IFR CIGS/VIS AFTERWARD. EXPECT UP TO 6 INCHES ACCUMULATION THRU
12Z AT THESE TERMINALS. SNOW WILL CONTINUE INTO WED AM...WITH MORE
SIGNIFICANT ACCUMULATION EXPECTED...ESPECIALLY AT KTRK.

FOR KRNO...OCNL MVFR CIGS/VIS IN SHRA THRU 02Z OTRW VFR. THEN AS CD
FNT MOVES THRU...MVFR CIGS/VIS THRU 06-08Z IN RA. WINDS WILL BE AN
ISSUE FROM THE SOUTH TODAT AT 20-25 KTS. HOWEVER...ANY LLWS WILL
DIMINISH AS LLVLS WILL BE UNSTABLE ENOUGH TO PROMOTE GOOD MIXING
ANY MINIMIZE ANY SHEAR LAYERS FROM DEVELOPING. EXPECT WINDS TO
GRADUALLY DIMINISH AS CD FNT MOVES THRU...ALTHOUGH THEY SHOULD
INCREASE A BIT AGAIN ON TUE.

KLOL...MORE VFR CIGS/VIS THRU 20Z...THEN LCL MVFR CIGS/VIS IN SHRA
THRU 06Z. ALSO...WITH INSTABILITY DEVELOPING...ISOLD TSRA ARE
POSSIBLE. WINDS WILL BE STRONGEST FROM 20-03Z TODAY NR 20 KTS FROM
THE SOUTH AND DO NOT EXPECT MUCH LLWS AT THIS TIME. WND SHIFT WITH
CD FNT AROUND 06Z TO WNW. MORE VFR CIGS TUE WITH SCT SHRA. WALLMANN

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...WINTER STORM WARNING FROM 10 AM THIS MORNING TO 4 AM PST
     WEDNESDAY FOR NVZ002.

     WIND ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR NVZ001-003-004.

CA...WINTER STORM WARNING FROM 10 AM THIS MORNING TO 4 AM PST
     WEDNESDAY FOR CAZ071-072.

     WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR CAZ073.

&&

HTTP://WEATHER.GOV/RENO

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE RENO NV
648 AM PST MON MAR 02 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 AM     SNOW             6 NNW BRIDGEPORT        38.34N 119.26W
03/02/2009  E4.0 INCH        MONO               CA   LAW ENFORCEMENT

            OVER DEVILS GATE SUMMIT ON U.S. 395. HEAVY SNOW STILL
            FALLING.

&&

JWALLMAN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RENO NV
655 AM PST MON MAR 02 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0654 AM     SNOW             1 WNW MAMMOTH LAKES     37.65N 118.98W
03/02/2009  M8.2 INCH        MONO               CA   TRAINED SPOTTER

            SPOTTER REPORTED 8.25 INCHES OF SNOWFALL IN THE PAST 24
            HOURS AT ELEVATION 8200 FT AND 0.88 INCHES OF LIQUID
            EQUIVALENT.

&&

KMOZLEY

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RENO NV
1021 AM PST MON MAR 02 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0942 AM     HEAVY RAIN       1 E SLOAT               39.87N 120.72W
03/02/2009  M1.50 INCH       PLUMAS             CA   TRAINED SPOTTER

            24 HOUR RAINFALL TOTAL AS OF 900AM.

0945 AM     HEAVY RAIN       TAHOE CITY              39.17N 120.14W
03/02/2009  M1.25 INCH       PLACER             CA   CO-OP OBSERVER

            24 HOUR RAINFALL TOTAL AS OF 700AM. 1 INCH OF NEW SNOW
            WAS ALSO REPORTED.

0957 AM     SNOW             SQUAW VALLEY            39.20N 120.22W
03/02/2009  M13.0 INCH       PLACER             CA   TRAINED SPOTTER

            12 HOUR SNOWFALL TOTAL AS OF 900AM AT 8200 FEET AT SQUAW
            VALLEY USA SKI RESORT. 1 INCH OF NEW SNOW REPORTED AT
            6200 FEET.

1000 AM     HEAVY SNOW       MOUNT ROSE SKI AREA     39.33N 119.89W
03/02/2009  M17.0 INCH       WASHOE             NV   TRAINED SPOTTER

            12 HOUR SNOWFALL TOTAL AS OF 900AM AT MOUNT ROSE SKI
            RESORT.

1000 AM     SNOW             2 SE INCLINE VILLAGE    39.23N 119.94W
03/02/2009  M6.0 INCH        WASHOE             NV   TRAINED SPOTTER

            24 HOUR SNOWFALL TOTAL AS OF 900AM AT DIAMOND PEAK SKI
            RESORT.

1002 AM     SNOW             ALPINE MEADOWS          39.17N 120.22W
03/02/2009  M12.0 INCH       PLACER             CA   TRAINED SPOTTER

            24 HOUR SNOWFALL TOTAL AS OF 945AM ON THE UPPER MOUNTAIN
            AT ALPINE MEADOWS SKI RESORT. 3 INCHES REPORTED AT THE
            BASE.

1006 AM     HEAVY SNOW       NORTHSTAR               39.28N 120.12W
03/02/2009  M16.0 INCH       PLACER             CA   TRAINED SPOTTER

            24 HOUR SNOWFALL TOTAL AS OF 1000AM AT THE SUMMIT. 6
            INCHES OF NEW SNOWFALL REPORTED AT MID-MOUNTAIN.

1018 AM     SNOW             HEAVENLY VALLEY         38.96N 119.89W
03/02/2009  M10.0 INCH       DOUGLAS            NV   TRAINED SPOTTER

            24 HOUR SNOWFALL TOTAL AS OF 1015AM AT HEAVENLY LAKE
            TAHOE SKI RESORT.

&&

SMCGUIRE